Bjørn Lomborg, an adjunct professor at the Copenhagen Business School, founded and directs the Copenhagen Consensus Center, which seeks to study environmental problems and solutions using the best available analytical methods. He is the author of The Skeptical Environmentalist and Cool It, the basis of an eponymous documentary film.

CANBERRA – Trade-offs are an inherent part of life. We all recognize this from our private budgets. To fix the roof, we may have to accept a less extravagant summer vacation. When we pick a cheaper wine, we can splurge on dessert. Trade-offs also pervade environmental policy: Cutting more of one pollutant, for example, leaves fewer resources...